Process and product for removing anions



Patented July 29,v 1941 UNITED STATES PATENT OFFICE raocess AND rnonccr roe REMOVING moms Robert. C. Swain, Riverside, Conn assignor t6 American Cyanamid Company, New York, .1 N. Y., a corporation of Maine No Drawing. Application December 6, 1940, Serial No. 368,855,

8 Claims.

This invention relates to anion-active materials and to the extraction of anions from fluid media.

An object of this invention is to provide a proc- Example 1 Parts Urea /2 moi) 30 Biguanide nitrate A mol) 41 Sodium carbonate (0.113 moi) 2 FormalinKP/g mois) (37% formaldehyde in water) 122 This mixture is charged into a suitable reaction vessel and refluxed on a steam bath, for example, for about 6 hours. About 20 parts of hydrochloric acid (18% HCl in water) are added to the resulting solution which is maintained at about 70-85 C. The gel thus formed is ground to a convenient size, such as about the size of a pea, and dried for 5 hours at about 50-60 C. The dried product is ground and screened so that the bulk ,of the material goes through 24 mesh and remains on mesh screens. The ground material may be thoroughly washed with dilute alkali followed by water, preferably distilled water, and it is then dried to substantially constant weight at any suitable temperature, for example, 110 C. The. packed density of the product is about 27.7 pounds per cubic foot.

A'fllter bed is prepared by filling a cylinder with the material prepared above which has been wetwith water. Water containing a relatively low concentration of hydrochloric acid (e. g., 0.01%) is passed through the bed slowly. The eiliuent remains approximately neutral and there is no test for chloride ions until the bed is exhausted. At this point the bed has absorbed acid,

the equivalent of about.8500 grains of calcium carbonate per cubic foot of resin. This value is generally designated as the capacity of the active material.

After the bed is exhausted it may be regenerated by washing with a dilute alkali, e. g.. a 2% solution of sodium carbonate, followed by distilled water and the bed is then ready for another cycle. During the second cycle the bed retains its capacity equivalent to about 8500 grains of calcium carbonate per cubic foot and in subse-' quent cycles, this value does not change very rapidly.

Example 2 1 Parts Urea moi) 40 Biguanide neutral sulfate A; moi) 37.5

Sodium carbonate 12 Formalin (l mois) (37% formaldehyde in water) 122 This mixture is charged into a suitable reaction vessel provided with an agitator and heated conveniently on a steam bath for about 6 hours at which time about 20 parts of hydrochloric acid (18% solution) are added to the hot solution. The resulting gel is broken up and dried for about 3 hours at around 55 C. and thenfor 5 /2 hours at about 100 C. The dried material is ground, screened and further processed according to Example 1. The resulting product has a packed density of about 34.6 pounds per cubic foot and exhibits a capacity equivalent to about 7000 grains of calcium carbonate per cubic foot of resin.

The product made according to this example is suitable for the removal of acid in the same manner as described in Example 1. It may be used not only in the extraction of hydrochloric acid but also in the extraction of other mineral acids such as sulfuric acid, mixtures of such acids as hydrochloric and sulfuric acids, organic acids such as acetic acids, oxalic acid, etc.

Formalin (3 mois) (37% formaldehyde in water) 243 These substances are reacted in the same general manner as described in Example. '1 by refluxing for about 6 hours followed by the addition of parts of hydrochloric acid (18% solution) to the hot solution. The resulting gel is Example 4 Parts Urea /2 mol) 30 Biguanide nitrate (A mol) 41 Sodium carbona 12 Formalin (1 mols) (37% formaldehyde in water) 122 These substances are reacted in the same general manner as described in Example 1 by refluxing for about 6 hours followed by the addition of 20 parts of hydrochloric acid (18% solution) to the hot solution. The resulting gel is ground and dried for about 4 hours at around 50-55" C. and then for about 4 hours at around 100 C. The dried material is further processed as described in Example 1 and the packed density of the ultimate product is found to be about 23 pounds per cubic foot and the material has a capacity for the extraction of acids equivalent to about 11,000 grains of calcium carbonate per cubic foot.

Example Parts Urea (1 mol) 60 Biguanide neutral sulfate 4 mol) 75 Sodium carbonate 24 Formalin (2 /2 mols) (37% formaldehyde in water) 202 ample l and the packed density of the ultimate product is found to be about 22.5 pounds per cubic foot and the material has a capacity for the extraction of acids equivalent to about 9000 grains of calcium carbonate per cubic foot.

Example 6 Parts Urea (1 mol) 60 Biguanide neutral sulfate mol) 75 Sodium carbonate 24 Formalin (3 mols) (37% formaldehyde inwater) Water These substances are reacted in the same general manner as described in Example 1 by refluxing for about 6 hours followed by the addition of 60 parts of hydrochloric acid (18% solution) to the hot solution. The resulting gel is ground and dried for about 4 hours at around 55 C. and

Example 7' Biguanide (free base) v (/4 mol) 26 Urea mol) 30 Formalin (i mols) (37% formaldehyde in water) 122 per cubic foot.

Example 8 Parts Biguanide neutral sulfate (V mol) 100 Melamine (V3 mol) 42.

Formal-in (2 mols) (37% formaldehyde in water)- 162 Sodium carbonate 32 The biguanide sulfate, formalin and sodium carbonate are charged into a suitable reaction vessel and heated for 10 minutes, as, for example, by means of a steam bath. The melamine is added and the resulting composition is refluxed for about 6 hours followed by the addition of 50 parts of hydrochloric acid (36% solution) to the hot solution". The resulting solution is allowed to stand overnight during which time a heavy precipitate forms but the solution does not gel. Upon heating the solution to about C. the precipitate dissolves, thereby forming a clear, somewhat viscous solution. To this solution an additional 10 parts of hydrochloric acid (36% solution) are added, thereby quickly producing a gel. The .gel is ground up and dried for about 4 hours at around 50 C, and then for about 24 hours at C. The dried material is further processed as described in Example 1 and. the packed density of the ultimate product is found to be about 28.3 pounds per cubic foot and it has an initial capacity for the extraction of acids equivalent to about 20,200 grains of calcium carbonate per cubic foot which on a subsequent run drops to about 18,000 grains of calcium carbonate per cubic foot.

Example 9 'Parts Biguanide neutral sulfate A, mol) 75 Melamine (1 mol) 126 Formalin (3 mols) (37% formaldehyde in water) 243 Sodium carbona 24 The biguanide sulfate, formalin and sodium carbonate are charged into a reaction vessel and heated to boiling to give a. clear solution. The melamine is added and thesolution is refluxed about 1% hours, thereby producing a slightly turbid viscous solution. 30 parts of hydrochloric acid (36% solution) are added to this solution.

substances which yield formaldehyde may be as the insolubilizing agent, other aminoplastics may be used. Among these are resins produced by condensing an aldehyde, e. g., formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde,

cinnamyl aldehyde, furfural, etc., with a urea or an aminotriazine or mixtures thereof. Ureas which may be used include urea itself, thiourea,

alkyl ureas, such as ethyl urea, etc. Examples of suitable aminotriazines are: melamine and its derivatives such as 2,4,6-triethyl and triphenyl triamino 1,3,5 triazines, 2,4,6-trihydrazin'o- 1,3,5-triazine, as well as triazines containing 1 or 2 amino groups such as the guanamines, e. g., formoguanamine, lauroguanamine, etc., 2-amino- 1,3,5-triazine and their substitution products. Obviously commercial mixtures of the various aminotriazines or mixtures thereof with urea and the like may also be used. One example of such commercial mixtures is the product obtained by heating dlcyandlamide sufilciently to obtain a significant amount of melamine, toether with other reactive aminotriazine bodies. Phenol-aldehyde condensation products, e. g., phenoland cresol-formaldehyde condensation products, may also be utilized as insolubilizing media. In some instances it may be desirable to react other substances with formaldehyde in conjunction with the biguanide and the insolubilizing agent, e. g.. phenol, aniline, phenylene diamine, dicyandiamide, guanidine and its salts, alkyl and aryl guanidines, etc.

Condensation products may be produced by any suitable process or with any desired combining ratio of aldehyde to the mixture of reactive materials including biguanide and urea, for example. Generally it has been found that the molal ratio of formaldehyde to the reactive materials should preferably not be too high as otherwise goorLgels are not easily obtainable.

Suflicient ion-active material should be included to provide a material having a substantial ion-active capacity. For this purpose the amount required varies widely with the solubility of the particular ion-active material used, the activity of the concentration of the ionic materials in the fluids to be treated, etc. In general a molal ratio of the biguanide, to the other formaldehyde-reactive component such as urea should preferably be between about 1:1 and 1:4, whereas if the latter material is melamine or the like the molal ratio should preferably be between about 3:1 and 1:3.

The biguanide may be used in the form of its salts such as the nitrate and sulfate as indicated in Examples 1-6 and 8-9 or in the form of the free biguanide as shown in Example 7. Furthermore other salts may be used, e. g., the carbonate, atcetate, formate, phthaiate, benzoate, chloride, e c.

The various aldehyde condensation products are preferably formaldehyde'condensation products. Obviously polymers of formaldehyde or used in place of formaldehyde itself.

My anion-active resins have a capacity for the extraction of anions from fluid media equivalent to about '7,'000-20,000 grains of calcium carbonate per cubic foot of resin.

My products are useful for many purposes, examples of which are: water softening, acid removal from water, acid removal from alcohol solutions, etc., purification of sugar juices, etc. My resins are especially suitable for the removal of acids, both organic and inorganic, from aqueous media. Apparently any acid, soluble in water may be separated by means of my resins in the manner described above. Furthermore my resins may be used to extract acids from fluid media other than water and may even be used for the extraction of acids from vapors.

Obviously many modifications and variations in the processes and compositions described above may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A process of removing anions from fluid media which comprises contacting a substantially insoluble anion-active material including a biguanide-aldehyde condensation product with a fluid medium containing anions.

2. A process of removing anions from fluid media which comprises contacting a substantially insoluble anion-active materialincluding a biguanide-formaldehyde condensation producttially insoluble anion-active material including a biguanide-formaldehyde condensation product with an aqueous medium containing anions.

4. A material active for the removal of anions from fluid media comprising an insolubilized biguanide-aldehyde condensation product.

5. A material active for the removal of anions from fluid media comprising a biguanide-formaldehyde condensation product insolubilized with a formaldehyde condensation product of a urea.

6. A material active for the removal of anions from fluid media comprising a biguanide-formaldehyde condensation product insolubilized with a formaldehyde condensation product -of an aminotriazine.

7. A material active for the removal of anions from fluid media comprising a biguanide-formaldehyde condensation product insolubilized with a formaldehyde condensation product of urea.

8. A material active for the removal of anions from fluid media comprising a biguanide-formaldehyde condensation product insolubilized with a formaldehyde condensation product of melamine.

ROBERT C. SWAIN. 

